Generally, air conditioning devices or air conditioning systems in a building control an indoor temperature with a predetermined indoor temperature. However, it is difficult to satisfy both comfort and energy saving with such an air conditioning control method. Various energy saving methods using technologies such as a temperature setting control, zone control, CO2 level control, and pre-cooling are suggested for air conditioning systems installed in a building. However, such control methods are mainly focused on energy saving and have limitations in controlling an indoor comfort temperature.